Safety is paramount in wellbore operations for the workers on a drill rig and for the environment. A drill rig may be placed on a ground surface or on a platform in the ocean, and a drill establishes the wellbore in the earth. Then, casings are cemented in place to separate the wellbore and the surrounding formation. Tubulars extend through the casing to extract resources from the earth. However, in some instances an unstable formation, an erratic downwell pressure, a drifting drill rig in the ocean, or another emergency can cause a catastrophic destruction of the wellbore. This can result in the uncontrolled release of natural resources which can destroy a drill rig, injure workers, and harm the environment.
A blowout preventer is a device typically positioned at a wellhead that can isolate a wellbore during an emergency and prevent the uncontrolled release of natural resources. Blowout preventers come in several varieties. In one example, a ram blowout preventer uses two pistons, one positioned on each side of the wellbore, to drive respective rams into each other in the wellbore to sever and slicklines, cables, and tubulars to isolate the wellbore. In another example, a doughnut-like structure is positioned around the wellbore, and pistons drive the doughnut into the wellbore to isolate the wellbore. Additional systems such as a subsea test tree are an intermediate solution that temporarily isolates the wellbore without using the blowout preventer.
However, these various systems rely on hydraulic power or other systems of power that can be interrupted in extreme environments like a marine environment. Thus, the failure of a power system can lead to the failure of a blowout preventer and/or a subsea test tree and to the harm of workers and the environment.